The present invention was developed in connection with a continuing effort to improve operating efficiency in automotive vehicle engines, particularly as to their fuel economy. Thus, while it is contemplated that the present invention, at least in its broader aspects, will be applicable to multicylinder engines of various types in various (e.g. nonvehicular) environments, the embodiments hereafter disclosed illustrate the invention applied to multicylinder, throttle controlled vehicle engines, such as conventional six and eight cylinder gasoline engines. The term "cylinder" is used broadly, usually interchangeably with "combustion chamber", and is not limited to reciprocating piston-in-cylinder engines but rather applies also to other engine types, e.g. rotary.
Conventionally, vehicles such as delivery trucks are powered by six or eight cylinder engines of sufficient size and power to adequately propel the vehicle under contemplated worst or substantially worst case operating conditions, e.g. under maximum engine load conditions as may arise from carrying full cargo up a relatively steep hill, or in accelerating from a standstill.
On the other hand, substantially less power, and engine displacement, is required under less demanding operating conditions, such as vehicle coasting or engine idle conditions, such as substantially steady state highway cruise conditions, or indeed other operating conditions needing only lesser power. It has been found that increased fuel economy can be obtained under such conditions if a substantial number of engine cylinders, i.e. combustion chambers, are rendered inoperative, as by maintaining their valves closed. Improved fuel economy has resulted in vehicle engines where half the cylinders are provided with disable-enable devices operating on the combustion chamber valves, hereafter called valve selectors, and the engine is alternatively operated on half or on all of its cylinders, for example three or six cylinders in a six cylinder engine or four or eight cylinders in an eight cylinder engine.
However, particularly in city or city-suburban driving, the amount of time the vehicle spends idling, coasting on closed throttle, or in low load, moderate speed steady state cruise may be quite limited. Instead, the vehicle may spend much of its time operating under intermediate conditions where the entire complement of cylinders (six or eight for example) is not needed, but must be kept operating because insufficient power is available in only half the complement of cylinders operating (e.g. three or four cylinders operating).
Accordingly, the objects of this invention include provision of:
A system for optimizing the number of cylinders which are operational at any given time in a multicylinder engine, in dependence on conditions under which the engine is operating.
A system as aforesaid in which cylinder enabling-disabling devices on a plurality of cylinders of a multicylinder engine need not be actuated or deactuated all at once but may be actuated or deactuated sequentially to provide for operation of the engine on a number of cylinders between minimum and maximum, so as to permit engine operation on less than all cylinders where operating conditions would not permit deactuation of all deactuable cylinders, and so as to permit, under a given set of operation conditions, a reduction in the proportion of the time spent in the all cylinders operating mode of the engine.
A system as aforesaid useable for controlling valve selectors on an engine so as to disable a given cylinder by permitting its valves to stay closed during engine operation.
A system as aforesaid particularly adapted to vehicle engines and capable of sensing vehicle parameters such as throttle setting, engine vacuum or load, engine or vehicle speed, and transmission gear engagement (e.g. third gear) and capable of selecting among several numbers of cylinders to be enabled in a manner to suit the then sensed vehicle parameters.
A system as aforesaid in which primary operation is to increase the number of operating cylinders when engine loading is high and decrease the number of operating cylinders when engine loading is lower, wherein intake manifold vacuum is used as a measure of engine loading, and wherein this primary operation is modified by other vehicle operating conditions, such as closed throttle, low or high vehicle speed, transmission gear engaged, or the like.
A system as aforesaid in which stepwise enabling and disabling of engine cylinders is carried out with bidirectional counting means.
Other objects and purposes of this invention will be apparent to persons acquainted with apparatus of this general type upon reading the following specification and inspecting the accompanying drawings.